Method of attaching insoles to lasts for lasting



Oct. 15, 1963 A. KAMBORIAN METHOD OF ATTACHING INSOLES T0 LASTS FDR LASTING Filed Feb. 12, 1962 y INVENTOR. 1,627?! jc'amarl'am United States Patent O 3,106,729 METHOD OF ATTAC lNG INSOLES T LASTS FOR LASTIN G Albert Kamborian, Newton Center, Mass, assignor to International Shoe Machine Corporation, Boston, Mass, a corporation of Massachusetts Filed Feb. 12, 1962, Ser. No. 172,503 9 Claims. (Cl. 12142) This invention relates to the manufacture of shoes and more especially to a method of securing an insole to the bottom of a last preparatory to lasting an upper thereto.

Various expedients have been employed to secure an insole to the bottom of a last preparatory to lasting and during lasting however, except for the use of tacks, other means that have been tried have proved impractical. The use of tacks nevertheless has certain disadvantages, to wit, the inconvenience of the extra operation involved in driving the tacks to secure the insole to the bottom of the last, removing the tacks following lasting and the necessity for careful inspection to make sure that no tacks are inadvertently left sticking up through the insole inside of the shoe.

The present invention has for its principal objects to provide a method of lasting shoes in which the insole is temporarily attached to the bottom of the last by adhesive means on the bottom of the last and/or the insole, characterized in that it is resistant to displacement of the insole except by a pull purposely applied at an angle to the plane of the adhering surfaces to separate them. The aforesaid means may comprise an adhesive applied to the bottom of the last and/or the insole activatable by heat and/or pressure. A releasing compound is preferably employed. The adhesive applied to the bottom of the last is of a kind which swells during activation and shrinks during de-activation and, by such shrinkage, pulls itself away from the insole thereby releasing the latter. The adhesive applied to the insole should be substantially inconspicuous and if not easily removable therefrom compatible with wearing the shoe. When adhesive is applied to both the last and insole it preferable is of a kind which adheres only to itself.

The invention will now be described in greater detail with reference to the accompanying drawings wherein:

FIG. 1 is an elevation of a last with a wear plate, a portion of the last and wear plate being broken away in section to show an insert of adhesive;

FIG. 2 is a plan View of the bottom of the last showing the location and shape of several inserts of adhesive;

'FIG. 3 is a plan view of an insole having a releasing compound applied to the surface which is to be attached to the bottom of the last;

FIG. 4 is a vertical section through a conditioner for activating the adhesive inserts in the bottom of the last;

FIG. 5 is an elevation of a support for a last and a pressure-applying pad for pressing an insole into engagement with the bottom of the last following activation of the adhesive inserts to cause it to adhere to the bottom;

FIG. 6 is a plan view of an insole with a layer of adhesive applied to the area which will have contact with the adhesive on the bottom of the last and with the entire area coated with a releasing compound; and

FIG. 7 is a transverse section taken on the line 7--7 of FIG. 6.

Referring to the drawings (FIGS. 1 and 2), there is shown a conventional wooden last L for making womens shoes, having applied to its bottom surface a wear plate P. In accordance with this invention and that described in my pending application Serial No. 156,245, filed December l, 1961, holes 10 are provided through the wear plate and into the wood of the last and these are filled 3,106,729 Patented Oct. 15, 1963 with a normally hard, non-tacky adhesive 12. The holes are illustrated as of circular and elongate cross-section. Preferably the holes of circular cross-section are located medially on the forepart and heel and the holes of elongate cross-section substantially parallel to the sides at the forepart and medially of the shank. Other arrangements however may be employed without departing from the scope of the invention. The adhesive may be anchored in the holes as shown in the aforesaid pending application or in any other suitable manner. The adhesive is characterized in that, when activated, it will become tacky, remain tacky for a predetermined length of time and then become non-tacky. During the activation and tacky state the adhesive expands or swells somewhat through the holes in the plate so that when an insole S is pressed against the bottom it will adhere to the tacky surface of the adhesive. During de-activation the adhesive retracts and pulls away from the insole, leaving it free, so that if an upper has been lasted to the insole the last may now be removed from the shoe. The bond between the insole and the bottom of the last is, on the one hand, comparatively weak in tension, that is a pull operating to separate the insole from the bot-tom and, on the other hand, relatively high in resistance to shear so that it resists accidental displacement of the insole during handling and lasting.

The adhesive used herein is a commercial polyamide resin manufactured and supplied by General Mills, Inc., under the name of Versalon XRSOl, and is activatable by heat, for example, inductive heat or radiant heat.

As herein illustrated, attachment of an uncoated insole to the bottom of the last is effected by first placing the last in a conditioner 16 (FIG. 4) provided with radiant or induction heating elements 20 to activate the adhesive. As soon as the adhesive is activated so that its upper surface swells through the openings in the wear plate and become tacky, the last is removed from the conditioner and placed on supports comprised, for example, of a toe rest 22 and heel pin 24, whereupon the insole S is placed on the bottom and a pressure-applying.

pad 26 is brought down into engagement with the insole to conform it to the bottom and to press it into engagement with the activated adhesive. Rods 28-28 support the pad for movement relative to the support and may, for example, be actuated by fluid motors. After the insole has been pressed into engagement with the last, the pad is lifted and the last removed for lasting of an upper to the insole. The adhesive holds the insole in place for a sufiicient length of time to effect the lasting operation and for some time thereafter depending upon the composition of the adhesive. At the end of the time limit imposed by the compound the adhesive becomes de-activated and non-tacky so that the last can be pulled out of the shoe without difficulty. As the adhesive cools it contracts, as related above, into the recesses, pulling itself away from the surface of the insole. It is within the scope of the invention to accelerate de-activation of the adhesive by suitable means depending upon the character of the adhesive.

To assist in detachment of the insole a very thin layer 14 (FIG. 3) of releasing compound may be applied to the insole. One such compound which has proved effective is that manufactured and supplied by General Mills, Inc., identified by the number RC5992-3 which is essentially a polyethylene. The compound is preferably applied by spraying on the insole in very small quantities so as to be substantially invisible and to leave no harmful or apparent residue which might adhere to the foot or cause a harmful reaction by contact with the skin under any circumstances. The releasing compound substantially eliminates any trace of adhesive that might be mechanically retained by the insole and yet is so thinly applied as to be completely unobjectionable. While the releasing compound referred to above is preferred, other known materials may be employed, such as silicone, Zinc stearite, wax, or the like, in the form of a liquid which may be sprayed on the insole or a powder which may be dusted thereon.

The adhesive on the bottom of the last may not sutfice to secure the insole to the bottom when certain insole materials are used and especially when they are stiff, such as may be the case with mens shoes and, in particular, work shoes. Hence, it is contemplated that adhesive may be applied to the insole in addition to the bottom of the last, responsive to pressure applied when the insole is laid against the bottom and/ or to heat activation temporarily to secure the insole to the last. As previously specified, the adhesive must be characterized in that it has relatively high resistance to shear and hence displacement of the insole relative to the bottom of the last so that the insole will not be accidentally knocked off during handling and lasting and relatively weak resistance to a pull applied at an angle to the adhering surfaces so as to be readily detachable by pulling the last away from the insole. As shown in FIGS. 6 and 7, the aforesaid adhesive means comprises an adhesive 12x applied to the insole S in the general area of the adhesive areas 12 on the bottom of the last. A layer of releasing compound 14 may or may not be employed and, if employed, is applied to the entire area of the insole to cover the adhesive-coated area and the uncoated areas of the insole. The adhesive may be applied in any suitable manner, for example by printing. When adhesive is applied to both the bottom of the last and the insole it is preferable to employ a kind that will adhere only to itself.

The adhesive which is applied to the insole must also be of a character which will not react to body heat or foot pressure to adhere to the foot.

When the adhesive employed is one activated by heat, the apparatus shown in FIGS. 4 and may be employed, supplemented by means for activating the adhesive on the insole. When the adhesive is of the kind activated by pressure alone, the apparatus shown in FIG. 5 is sufiicient to attach the insole to the bottom of the last.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

I claim:

1. The method of temporarily attaching an insole to the bottom of a last preparatory to lasting the margin of an upper thereto comprising, providing a last with means substantially permanently attached to the bottom repeatedly activatable to effect an adherence of successive insoles to the bottom for lasting of uppers thereto, said means providing a temporary bond which is relatively resistant to displacement of the insole in the plane of the adhered surfaces and relatively easily broken by a force applied at an angle therto, attaching the insole to the bottom of the last by means of said activatable means, and detaching the insole from the bottom by stripping the lasted shoe from the last by force applied at an angle to the bottom.

2. A method according to claim 1, comprising employing an adhesive which is activatable by an application of heat and becomes de-activated upon cooling, and attaching the insole by an application of heat while the insole is in contact with the bottom.

3. A method according to claim 1, comprising e1nploying an adhesive which is activated by pressure, and attaching the insole by an application of pressure to the insole while in contact with the bottom of the last.

4. A method according to claim 1, comprising employing an adhesive which, on the one hand, is relatively weak in tension and, on the other hand, is relatively strong in shear.

5. The method of temporarily attaching an insole to the bottom of a last preparatory to lasting the margin of an upper to an insole comprising, providing a last with a quantity of normally quiescent adhesive secured to its bottom, providing an insole with a quantity of compatible adhesive secured to a corresponding area of the side to be fastened to the last, placing an insole on the bottom and causing it to be adhered thereto by activation of the adhesive on the bottom and the insole, said adhesive being of a character that will relinquish its hold under a relatively low pull applied at an angle to the plane of the surfaces.

6. The method of temporarily attaching an insole to the bottom of a last preparatory to lasting the margin of an upper to an insole comprising, providing a last and insole with means on their respective surfaces which are mutually adherent when activated, said means being of a character that is readily detachable by a separating force applied at an angle to the surfaces, applying a releasing compound to one or both of the surfaces, placing an insole on the bottom of the last, and effecting adhesion of the mutually adhesive means by appling pressure.

7. The method of temporarily attaching an insole to the bottom of a last preparatory to lasting the margin of an upper thereto comprising, providing a last with a plurality of areas of normally non-tacky adhesive, of the kind that is capable of being activated for a predetermined length of time so as to be tacky and, at the end of said time, to become substantially non-tacky, applying a releasing compound to the surface of the insole to be temporarily attached to the last, activating the adhesive areas on the bottom of the last, and pressing the surface of the insole coated with the releasing compound into engagement with the bottom of the last.

8. The method of temporarily attaching an insole to the bottom of a last preparatory to lasting the margin of an upper thereto comprising, providing a last with a plurality of cavities containing a solid, normally nontacky adhesive of the kind which may be activated to become tacky for a predetermined length of time and at the termination of which it becomes substantially nontacky, applying a thin, substantially inconspicuous releasing compound to the surface of the insole to be attached to the last, activating the adhesive contained in the recesses at the bottom of the last, and pressing the coated side of the insole into engagement with the bottom of the last.

9. The method according to claim 8, wherein the adhesive increases in volume during activation so as to project from the recesses and contracts during de-activation so as to recede into the recesses and detach itself from the insole.

Blake Jan. 11, 1921 Nolan Feb. 15, 1955 

1. THE METHOD OF TEMPORARILY ATTACHING AN INSOLE TO THE BOTTOM OF A LAST PREPARATORY TO LASTING THE MARGIN OF AN UPPER THERETO COMPRISING, PROVIDING A LAST WITH MEANS SUBSTANTIALLY PERMANENTLY ATTACHED TO THE BOTTOM REPEATEDLY ACTIVATABLE TO EFFECT AN ADHERENCE OF SUCCESSIVE INSOLES TO THE BOTTOM FOR LASTING OF UPPERS THERETO, SAID MEANS PROVIDING A TEMPORARY BOND WHICH IS RELATIVELY RESISTANT TO DISPLACEMENT OF THE INSOLE IN THE PLANE OF THE ADHERED SURFACES AND RELATIVELY EASILY BROKEN BY A FORCE APPLIED AT AN ANGLE THERTO, ATTACHING THE INSOLE TO THE BOTTOM OF THE LAST BY MEANS OF SAID ACTIVATABLE MEANS, AND DETACHING THE INSOLE FROM THE BOTTOM BY STRIPPING THE LASTED SHOE FROM THE LAST BY FORCE APPLIED AT AN ANGLE TO THE BOTTOM. 